This application claims foreign priority benefits of applicant's Japanese Patent Application Serial No. JP PA 2003–48873, the entire disclosure of which is incorporated herein by reference.
1. Field of the Invention
The invention relates to a door apparatus, which locks and unlocks a door when opening and closing the door.
2. Description of the Related Art
The construction of a door apparatus of the related art will be described with reference to the drawings. FIGS. 5A and 5B are schematic views of a door apparatus. FIG. 5A shows a door closed and FIG. 5B the door open. FIGS. 6A and 6B are views of a lock device. FIG. 6A shows a locked state and FIG. 6B shows an unlocked state. FIG. 7 is a flow chart showing a control algorithm for opening a door of the related art.
As shown in FIGS. 5A and 5B, the door apparatus has a door 1, a linear motor 2, a lock device 3, a control unit 4, stoppers 5, and a holder part 6.
The door 1 is constructed to move in opposite opening and closing directions (the left and right directions in FIGS. 5A and 5B) between a closed state shown in FIG. 5A and an open state shown in FIG. 5B. The direction in which the door 1 is opened (from the state shown in FIG. 5A to the state shown in FIG. 5B) will be called herein the opening direction, and the direction in which the door 1 is closed (from the state shown in FIG. 5B to the state shown in FIG. 5A) will be called the closing direction.
The linear motor 2 is one specific example of a door driving device, and applies a thrust or thrust force to the door 1 so that by door movement the door 1 moves and performs an opening operation or a closing operation.
The lock device 3, which will be further discussed later, is mechanically constructed selectively to perform a locking operation or an unlocking operation on the door 1.
The control unit 4 controls the linear motor 2 and the lock device 3 in accordance with door opening and closing instructions from a control part (not shown).
The stoppers 5 prevent the door 1 from suffering a strong shock even if the door 1 opens and closes energetically and hits the ends of its range of motion in its opening and closing directions.
As shown in detail in FIGS. 6A and 6B, the lock device 3 also has a holder part 6 (shown in FIGS. 5A and 5B), a locking pin 7, a solenoid 8, a locking pin mounting 9, and a locking sensor 10.
The holder part 6 is fixed to the door 1 (see FIGS. 5A, 5B), and has a lock hole 6a (see FIGS. 6A, 6B) into which the locking pin 7 can pass.
The locking pin 7 is inserted into the lock hole 6a of the holder part 6 to mechanically fix the door 1.
The solenoid 8 supplies a thrust for deploying or withdrawing the locking pin 7.
The locking pin mounting 9 mechanically connects a moving part of the solenoid 8 to the locking pin 7, and transmits the thrust from the solenoid 8 to the locking pin 7. The locking pin mounting 9 also allows a contact arm of the locking sensor 10 to move, as the locking pin mounting 9 moves up and down.
The locking sensor 10 is provided to check the position of the locking pin 7. As shown in FIG. 6A, when the locking pin is in the locked state, the locking sensor 10 outputs an ON-state signal because the locking pin mounting 9 has descended and lowered the contact arm. As shown in FIG. 6B, when the locking pin 7 is withdrawn from the lock hole 6a so that the lock device 3 is in the unlocked state, the locking sensor 10 outputs an OFF-state signal because the locking pin mounting 9 has ascended and allowed the contact arm to be raised. These ON-state and OFF-state signals are outputted to the control unit 4.
The operation of the lock device 3 when the door 1 is opened (moved from the closed state to the open state) will now be explained.
When the door 1 is closed, as shown in FIG. 6A, the locking pin 7 is inserted in the lock hole 6a of the holder part 6. When the locking sensor 10 detects this position of the locking pin 7, the sensor outputs a signal indicating that the sensor is in the ON state (corresponding to the locked state of the lock device 3). The control unit 4 detects the ON-state signal outputted from the locking sensor 10 and recognizes the locked state.
If the control unit 4 has received a door opening instruction for opening the door 1, the control unit 4 first controls the lock device 3 to shift from the locked state to the unlocked state, and then controls the linear motor 2 to open the door 1. This control now will be described. As shown by the flow in FIG. 7, the solenoid 8 is driven to perform an unlocking operation by lifting the locking pin 7 from the lock hole 6a (step S100).
Along with the locking pin 7, the locking pin mounting 9 also rises, and the lock device 3 assumes the unlocked state shown in FIG. 6B. In the unlocked state, the locking sensor 10 is in its OFF state, and outputs an OFF-state signal to the control unit 4. The control unit 4 always determines whether the locking sensor 10 has shifted to its OFF state (i.e. whether the signal outputted from the locking sensor 10 has shifted from the ON-state signal to the OFF-state signal) (step S101). When the control unit 4 does not detect the ON-state signal, it then infers that the unlocking operation has not been carried out and returns to step S100 before it drives the solenoid 8 again. When the control unit 4 has detected the OFF-state signal, it controls the linear motor 2 to apply a thrust force to the door 1 in the opening direction (step S102). The linear motor 2 then opens the door 1 to its open state (see FIG. 5B).
When the door 1 is to be closed, the control unit 4 performs the reverse operation. That is, it controls the linear motor 2 to apply a thrust force to the door 1 in the closing direction of the door 1 and controls the lock device 3 to perform a locking operation. Such is a door apparatus of the related art.
As another door apparatus, of the prior art, using a linear motor and a lock device, there is also the apparatus disclosed in JP-A-10-193977 (corresponding to U.S. Pat. No. 5,927,015), for example.
In the lock mechanism of the disclosed in JP-A-10-193977, which is described therein at Paragraph Numbers 0016 and 0017 and illustrated in FIGS. 4 through 7 thereof, a transfer rod 26 of a linear induction motor (LIM) actuator 25 holds a door panel 17 firmly in a closed position by moving a lock assembly 40 to a locked state.
As another example of the prior art, there is also the technology described in the non-patent publication “Development of Linear Motor Driven Door System for Commuter Train” published by Sato, Kouzu, Suzue, and Inage at pages 359–362 of the 1999 Electrical Engineering Society Industrial Application Section Conference Lecture Articles. As shown in FIG. 1 and FIG. 6 thereof, this non-patent publication describes a technology where a door system has a direction converting device for mechanically dividing a thrust generated by a single linear motor so as to open a double door, and a door locking device for locking and unlocking this direction-converting device.
In these prior art technologies, there is no consideration of a problem in the operation of the lock device. This problem will be described with reference to the drawings.
FIG. 8 is illustrates a problem of a lock device. In the locked state shown in FIG. 8, it sometimes happens that due to the state of mounting of the lock device 3 with respect to the door 1, or of the door 1 impacting with the stoppers 5, the center of the lock hole 6a may become misaligned with respect to the locking pin 7, so that they are relatively positioned such that in the locked state, the locking pin 7 and the cylindrical boundary surface of lock hole 6a make contact and create a frictional force.
In this case, there is the problem that it takes much longer than normal for the locking pin 7 to rise, and in bad cases the locking pin 7 does not rise at all.
Because of this kind of situation in the prior art, a solenoid 8 that produces a thrust force large enough to overcome the frictional force between the locking pin 7 and the boundary of the lock hole 6a has been used. However, this creates a problem that the size and cost of the apparatus increase.
When this problem state continues, the locking sensor 10 remains in its ON-state and the steps S100 and S101 of FIG. 7 are repeated. This also causes a problem that the solenoid 8 continues to be energized, thereby resulting in an overheating of the device.